225 Oil Pressure

MY brand new rebuilt 225 runs great and sounds good. Put the melling high volumn oil pump in it.
PROBLEM is it only registers 10 to 15 pounds of oill pressure. I had a mechanical gauge and thought it must be bad so I bought a Stewart Warner electronic gauge. 10 lbs. The sender is mounted in the hole 6 inches toward the firewall fromm the pump.
If the pressure was really low the lifters should be macking a ruckus and they sound fine.
Any help?

 

any adaptors used could make a lower reading. I have 25@idle cold or not.

 

Dang, I hate to hear stories like this. BTDT!

What happens when you revv the engine? How about when warm at idle? (Warning: unorthodox advice coming...)

If you actually have only 10 lbs. of oil pressure, and are still unsure whether or not to believe your gauges, try this last-resort trick: run engine to operating temp; remove the oil pressure tube from the gauge, and pull it from the firewall. Set it into a clean bucket/receptacle. Have an assistant start the engine. Watch the oil squirt from the oil sending unit tube into the bucket. If pressure's low, it'll only drip out, and you can thereforeward trust your gauges. If oil streams out heavily to where you're shouting "oh $hi+", then perhaps the gauges aren't reporting proper pressure. Have the assistant slam on the gas pedal once; you should notice a pronounced squirt. This response, in a rebuilt engine, is important to know.

Sounds funny and messy, but you'll be able to mentally "gauge" how much pressure is actually going on by looking at the squirt. You'll know. If pressure is really that low, it'll only dribble/spit out at idle, which means your gauges can likely be trusted. Revving the engine should result in a more pronounced squirt. Only do this for ~20 seconds or so, no more! Refill oil when done.

Unorthodox, yes, but effective in a pinch if you're not sure what to believe. There are probably other effective, less-messy methods, but I can't think of them at the moment. (LOL)

Also, if you don't already have this, consider upgrading to a gauge with the zero at 8 o'clock to the max at the 4 o'clock position. Gives you a much broader view throughout its normal variations. The 10 o'clock to 2 o'clock gauges conceal more than they reveal.
-Alan

 

I looked up the oil presure spec in Ludel and it shows 33 pounds at 2400 RPM. Since I had 20 pounds with the old mechanical I'm going to do a few things.
First I'm going to reinstall the new SW electrical making sure all my connections are good, especially the grounds.
If that dosn't help I'm going to try the stiffest melling pressure relief spring. If that doesn't work I'll pull the cover and check the gears.

 

Thanks,
A local guy who I have confidence in built the motor.
On the 225 the pump is on the outside so it is easy to work on. And I'll be checking everything today.

 

I would check to make sure the pressure relief plunger moves freely in the bore, and that it doesn't hang up in a worn bore.
I have a spare oil pump housing cover that I carry (and gears) if you need to eliminate possibilities; free to use if you need it.
Somtimes the axle housing can come up and hit the oil pump cover, damaging it. This usually results in high pressures, but I suppose the opposite could happen as well.

the correct gasket should also be paper thin, not very thick.

 

Thanks Jim,
I am eliminating potentials one at a time.
I wish Melling was open today.
I really like Summit for everything but Technical help.